The Japanese and European Union governments have instituted policies requiring industries to remove environmentally hazardous materials from their products, thus creating “green” products. One material targeted, lead (Pb), is a major constituent of plastic ball grid array (PBGA) solder balls and the solder paste historically used to attach the component to the board. The lead-containing solder paste commonly used is eutectic tin-lead (63 wt % Sn/37 wt % Pb) and the ball is usually eutectic tin lead or also includes 2% Ag (62 wt % Sn/36 wt % Pb/2 wt % Ag). As a result of such legislation, the semiconductor industry is moving to lead-free solders. Lead-free solders being studied in the industry generally include elements such as tin (Sn), silver (Ag), copper (Cu), indium (In), antimony (Sb) and bismuth (Bi).
To comply with this legislation, companies need to be able to easily distinguish between lead-free and lead-containing materials. For example, assemblers may want to verify that the semiconductor device is lead-free before soldering it to their printed circuit board (PCB), especially if the composition of a terminal is unknown. In addition, there is a risk of mixing lead-free (Pb-free) and lead-containing (Pb-containing) balls when attaching them to ball grid array (BGA) substrates so testing of the material composition may be desired to avoid this risk. One method of testing to determine if lead is present includes performing analytical testing, but this increases costs, time, and complexity of manufacturing.
Another lead-testing (Pb-testing) method, used most often in homes to test paint and china dishes, includes using test swabs, such as those available in a lead-test kit sold by LeadCheck®. But test swabs require manually testing of each material. This results in increased cost and increased cycle time. Thus, a need exists for a way to detect if a material is lead-free or not without increasing cycle time and increasing cost.
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